Drilling fluid

ABSTRACT

An aqueous drilling fluid dispersant and a method of drilling wells using as the drilling fluid dispersant a dihydroxy substituted phenyl alkyl ketone, namely, 1,2-dihydroxy-4acetylbenzene, 1,2-dihydroxy-4-propionylbenzene, and mixtures thereof.

United States Patent Kablaoui et al.

[151 3,657,122 1 Apr. 18,1972

[54] DRILLING FLUID [72] Inventors: Mahmoud S. Kablloul; .Ilck H. Kohhn,

both of Wappingers Falls, NY.

[73] Assignee: 'Ienco,1ne., New York, NY.

[22] Filed: June 16, 1970 [21] Appl. No.: 46,805

{52] US. Cl. .152/8-5 C, 252/351 [51] lnt.Cl. ..Cl0m 3/14 [58] Fleltl olSearch ..252/8.5 C, 351

[56] References Cited UNITED STATES PATENTS 3,524,813 8/1970 Kolaian ..252l8.$ C

1,999,766 4/1935 Lawton et a1. ......................252/8.5 A 2,333,133 11/1943 Wayne ....252/8.5 C 3,535,239 10/1970 Kolaian ..2$2/8.5 C

Primary Examiner-Herbert B. Guynn Attorney-Thomas 1-1. Whaley, Carl G. Reis and James F. Young [57] ABSTRACT 3 Claims, No Drawings This invention relates to a novel aqueous drilling fluid for drilling wells through sub-surface formations by means of well drilling tools, and particularly to such an aqueous well drilling fluid having improved dispersibility as a result of containing therein a novel dispersant as hereinafter more fully described. The invention is also concerned with a method of drilling well employing the novel aqueous drilling fluid.

Drilling fluids, or muds as they are sometimes called, are slurries of clayey solids used in the drilling of wells for tapping underground collections of oil, gas, brine or water. Such fluids have a number of different functions, the most important of which are to assist in the removal of cuttings from the well, to seal ofi formations of gas, oil or water which may be encountered at different levels, to lubricate the drilling tool and drill pipe which carries the tool, and to hold the cuttings in suspension in event of shut-downs in drilling.

An ideal drilling fluid is a thixotropic collodial system, i.e., a fluid which on agitation or circulation (as by pumping or otherwise), has a measurable relatively low viscosity and is free flowing (not plastic), particularly at high temperatures; but when such agitation or circulation is halted, the fluid sets or gels. The rate of gel formation is such as to permit the cuttings to fall only a short distance before the gel structure is sufficiently strong to support them.

When such a drilling fluid having the proper viscosity, the proper gel rate and proper gel strength is circulated through a well bore, it has a sufficiently high viscosity to carry the amounts ranging from about 01 pound to about pounds per barrel of drilling fluid. In general, it has been found that amounts less than 01 pound per barrel do not produce completely satisfactory results in terms of dispersing activity whereas amounts above about l0 pounds per barrel are economically unattractive and no improved results are obtained therewith. A preferred range for dihydroxy substituted phenyl alk yl ketones of the present invention is from about 0.25 to about 7 pounds per barrel of drilling fluid for most' 0 consistent results and efiiciency.

Yield Point (Y?) is calculated by subtracting the Plastic Viscosity (PV) from the Fann Viscosity reading at 300 rpm. Plastic Viscosity (PV is obtained b calculation, subtracting the Fann reading at 00 rpm from e 600 rpm reading. Apparent Viscosity (AV) is equal to one half of the Fann Viscosity reading obtained at 600 rpm. The fluidity of a mud can be back calculated from these data, the results being expressed in Fann Viscosity at 600 rpm and 300 rpm for a direct reading viscosimeter.

The properties of the base muds are shown in the table.

The test data set forth in the following table indicate die surprising advantages of the dihydroxy substituted phenyl alkyl ltetones of the present invention and demonstrate the beneficial results of same in improving the dispersibility of drilling fluids.

Representative physical properties of drilling fluids both before and after addition of the dihydroxy substituted phenyl alkyl ketones of the present invention are shown in the table. In each example the amount of material or materials added to the base mud, if any, is shown, expressed in terms of pounds of cuttings and sand from the bottom of the hole to the surface material per barrel of drilling fluid.

Amount (lbsJbbL) and type Ap. vis., Ex. Additional additive, lbs. Type mud dispersant PV 1? ope. pH

Basernud 6 78 I 0. 25A 23 21 33. 5 8. 3 1 L H 0.60 23 25 35.5 8.2 1.0 16 28 30 7. 3 0. 25A 10 19 2B. 5 9. 4 2 Caustic to attain pH 9.4-9.5.-. LpH 0. 60 26 23 37. b 9. 4 1. 0 21 81 36. 6 9. 5 3 4.0llrne MOD BC L... 26A 14 30 2'3 I hpH=Low pH mud. 1 OD SO-Modifled Shale Control mud.

A Lz-dlhy droxymetylbensene.

and it has a gel rate such as to allow the cuttings and sand to settle in a settling pit. On standing in a quiescent state, it develops sufficient gel strength to prevent the settling of the cuttings, sand or weighting material, etc., in the well bore when it becomes necessary to discontinue circulation for any appreciable period of time. Such a fluid is also characterized by its ability to fonn a mud cake on the borehole wall, thereby assisting in sealing off the traversed formations and inhibiting so-called water loss, i.e., loss of water from the drilling fluid.

One of the principal problems in mud chemistry is the production of suitable drilling fluids having satisfactory dispersibility, and the necessary thixotropic properties discussed above.

In accordance with the present invention the problems of dispersibility in aqueous drilling fluids can be solved by incorporating in an aqueous drilling fluid as the dispersant a dihydroxy substituted phenyl alkyl ketone selected from the group consisting of l,2-dihydroxy4-acetylbenzene, 1,2- dihydroxy-4-propionylbenzene, and mixtures thereof.

It is known from the article appearing in Zhur. Prikladl Khem. 35, pages 638-647 (1962), "Organic Viscosity Redu cers in Clay Solutions" by D. Tischenko and S. Fleisher (CA,

57, 249lg, I962), that the ortho-dihydroxybenzenesulfonic acids, the ortho-dihydroxyalpha-toluenesulfonic acids and water soluble salts thereof are viscosity reducing agents in clay laden drilling fluids whereas the corresponding meta-and paradihydroxybenzenes including the corresponding sulfonic acid derivatives and water soluble salts thereof are ineffective viscosity reducing agent for aqueous drilling fluids.

The dihydroxy substituted phenyl alkyl ketones of the present invention may be added to an aqueous drilling fluid in The Table above shows that the dihydroxy substitued phenyl alkyl ketones of the present invention are effective dispersants in low pH and modified shale control drilling fluids at concentrations of from 0.25 to 2.5 pounds per barrel.

A modified shale control drilling fluid contains lime and caustic but is free from an added water soluble calcium salt. A modified shale control drilling fluid containing lime, caustic, if needed, and the novel dispersants of the present invention will provide the same beneficial results as achieved with the shale control drilling fluid of Weiss and Hall, US. Pat. No. 2,802,738, i.e., stabilizing and hardening the shale fonnations in contact therewith. This surprising result is accomplished in the absence of the added water soluble calcium salt required by the Weiss and Hall patent to attain the necessary shale control chemistry needed to stabilize and harden the shale formations in contact therewith.

We claim:

1. An aqueous drilling fluid containing clay solids and as the dispersant from about 0.1 to about 10 pounds, per barrel of drilling fluid, of l ,2-dihydroxy-4-propionylbenzene.

2. An aqueous drilling fluid as claimed in claim I wherein the l,2-dihydroxy-4-propionyl benzene is present in the drilling fluid in an amount of from about 0.25 to about 7 pounds per barrel of drilling fluid.

3. [n a method of drilling wells wherein a drilling fluid is d through the well in contact with earth formations durmg the drilling operation, the improvement which comprises contacting said earth formations with an aqueous drilling fluid containing clay solids and as the dispersant at least 0.1 pound per barrel of drilling fluid of 1,2-dihydroxy-4-propionylbenzene. 

2. An aqueous drilling fluid as claimed in claim 1 wherein the 1,2-dihydroxy-4-propionyl benzene is present in the drilling fluid in an amount of from about 0.25 to about 7 pounds per barrel of drilling fluid.
 3. In a method of drilling wells wherein a drilling fluid is passed through the well in contact with earth formations during the drilling operation, the improvement which comprises contacting said earth formations with an aqueous drilling fluid containing clay solids and as the dispersant at least 0.1 pound per barrel of drilling fluid of 1,2-dihydroxy-4-propionylbenzene. 